Here is what David Lean and Freddie Young used for Ryan's Daughter. Don't know if this is of any help but if nothing else it's interesting. Lean used Panaflex 65mm cameras all year round on the beach when shooting the film in Ireland. As you can see the camera is unprotected by even a sheet of plastic, at least when they took the publicity stills. For the storm sequence they put the camera inside a big barrel like container, probably designed for the production. It even had a maritime spinning centrifugal disk at the front to throw off the sea spray. Hope this helps.